Rovergauge Long Term Trim +100% Poor MPG
Discussion
Hello gentlemen,
Had my new Chim just over a week and she's been running great but getting terrible MPG. 11.4 MPG on first calculation which I know is off for a 400 driving around town and mostly on 30/40 roads. Yes yes don't buy a Chimaera for the fuel economy but as a daily drive I want her to be as good as she can be.
Hooked the car up to Rovergauge and got the following fault codes. Reset them and they didn't come back whilst letting the car idle for a while and gently revving up.
Short term fuel trim seems to be cycling around 0% as you'd expect, long term trim though once warm at idle is fully saturated at +100% on both banks. AFM reading is 3% linear and 30% direct. Everything else seems quite normal. Any suggestions as to where to look next and what could be the possible cause of this long term fuelling issue?
Alex
Had my new Chim just over a week and she's been running great but getting terrible MPG. 11.4 MPG on first calculation which I know is off for a 400 driving around town and mostly on 30/40 roads. Yes yes don't buy a Chimaera for the fuel economy but as a daily drive I want her to be as good as she can be.
Hooked the car up to Rovergauge and got the following fault codes. Reset them and they didn't come back whilst letting the car idle for a while and gently revving up.
Short term fuel trim seems to be cycling around 0% as you'd expect, long term trim though once warm at idle is fully saturated at +100% on both banks. AFM reading is 3% linear and 30% direct. Everything else seems quite normal. Any suggestions as to where to look next and what could be the possible cause of this long term fuelling issue?
Alex
Thanks for that Mark, I'll see if I can run Rovergauge this evening when I get in and see if the faults have reappeared after a day's driving.
Had a look at the plug on cylinder 2 and it was a bit wet and sooty looking. I'll check the others for condition later after work. Doesn't feel like she's misfiring.
Surely a faulty AFM could cause those fault codes but it's weird that it looks like it's working correctly in RG.
Had a look at the plug on cylinder 2 and it was a bit wet and sooty looking. I'll check the others for condition later after work. Doesn't feel like she's misfiring.
Surely a faulty AFM could cause those fault codes but it's weird that it looks like it's working correctly in RG.
Haven't probed the AFM yet but should be able to borrow a multimeter tomorrow to take a look.
Drove home from work today, car ran fine until stopped in traffic for a while. Became very hesitant on acceleration at one point and idle became erratic hunting from 500rpm to 1200rpm and dropping to 500rpm when coming to a stop from 30mph. I suspect in the baking sun something wasn't liking the heat.
Smelt very rich but cleared by time I got home. Let her cool off a touch. Plugged in RoverGauge and it dumped out the following faults this time:
Cleared the codes. Ran the car for a while and logged the data, ran beautifully and nothing seemed amiss. Fuel temperature was previously at about 60C and dropped slowly to 40C whilst idling with the bonnet up.
Long term Lambda had dropped this time to roughly +20% on both banks and short term Lambda was fluctuating around -10% to +20%.
Pulled the plugs on the even firing side and they looked all like this:
Cleaned off with a bit of petrol, replugged both AFM and TPS and drove her to get some fuel. Drove beautifully. Will see what she does tomorrow, think I'm going to need to log a drive though to catch it in the act.
Drove home from work today, car ran fine until stopped in traffic for a while. Became very hesitant on acceleration at one point and idle became erratic hunting from 500rpm to 1200rpm and dropping to 500rpm when coming to a stop from 30mph. I suspect in the baking sun something wasn't liking the heat.
Smelt very rich but cleared by time I got home. Let her cool off a touch. Plugged in RoverGauge and it dumped out the following faults this time:
Cleared the codes. Ran the car for a while and logged the data, ran beautifully and nothing seemed amiss. Fuel temperature was previously at about 60C and dropped slowly to 40C whilst idling with the bonnet up.
Long term Lambda had dropped this time to roughly +20% on both banks and short term Lambda was fluctuating around -10% to +20%.
Pulled the plugs on the even firing side and they looked all like this:
Cleaned off with a bit of petrol, replugged both AFM and TPS and drove her to get some fuel. Drove beautifully. Will see what she does tomorrow, think I'm going to need to log a drive though to catch it in the act.
Steve_D said:
When you do the log it may be worth restricting the channels you log as the ECU is pretty low tech and can't handle trying to log too much data.
Yeah she idles a lot nicer when on her own, runs a bit more like a bag of bolts when tethered to RoverGauge.If I can install the drivers on my work laptop I'll run a log on the way home tonight but I'm working late so don't expect mega temperatures in traffic.
Plugs are B7ECS. I'm starting to think it's the AFM playing up more than anything. Went to log a drive on the way home and the car stalled with the laptop plugged in when I started up and the laptop crashed and rebooted so I'll try logging fewer things in the morning when I have another go.
Did manage to see the TP move from 5%to 85% smoothly through its range though before stating the engine in Rovergauge. Is that normal?
Did manage to see the TP move from 5%to 85% smoothly through its range though before stating the engine in Rovergauge. Is that normal?
Ok new, but hopefully related problems on the way home from work today. The car started fine but then immediately wanted to idle at about 400rpm, stalled itself after a few seconds, restarted and wanted to not idle again so tried to coax it with some throttle- felt like it wasn't doing anything, but slowly the car started to perk up then settled after about 15 seconds at her usual 900rpm idle with no apparent problems.
On the way home sat in traffic for about 10-15 minutes once up to temperature just crawling forward in the sun. Pulling away from the lights I'm easing the throttle in in 2nd from 15mph up to 20mph when it feels like I've got no throttle then all of a sudden slam! Throttle response back, the kind of impact you get from fuel starvation.
Car is fine for the rest of the journey.
On the way down my road I boot it in 2nd and it feels like there's just no power. Almost like there's 50% power but with all the noise of WOT. Am I in limp home mode?
Sod's law I left the laptop at work and so missed the opportunity to log when she started misbehaving!
On the way home sat in traffic for about 10-15 minutes once up to temperature just crawling forward in the sun. Pulling away from the lights I'm easing the throttle in in 2nd from 15mph up to 20mph when it feels like I've got no throttle then all of a sudden slam! Throttle response back, the kind of impact you get from fuel starvation.
Car is fine for the rest of the journey.
On the way down my road I boot it in 2nd and it feels like there's just no power. Almost like there's 50% power but with all the noise of WOT. Am I in limp home mode?
Sod's law I left the laptop at work and so missed the opportunity to log when she started misbehaving!
Finally this problem climaxed into the car stalling at cold startup and running like an absolute pig being coaxed home using the clutch to slip into every gear. Shunting like I've never ever seen before but finally caught her in the act!
MAF reading 0% direct and no difference when unplugged. No power over 3,400rpm. I think my AFM is dead
MAF reading 0% direct and no difference when unplugged. No power over 3,400rpm. I think my AFM is dead
Ok fitted all new plugs last night and the car seemed ok on a little shakedown this morning. AFM is alive again no longer showing 0% direct but a new one is on order. I suspect it's become temperature sensitive but can't confirm yet because my crap work laptop crashes when running RoverGauge so I'm borrowing the girlfriend's laptop to log a full run as I know it doesn't crash when running RG.
Tidied up a few things in the engine bay this morning, cable tied one of the lambda wires away from the manifold as it was touching and I imagine getting very hot. Tried wiggling all the wiring in the back of the AFM whilst running and made no difference so I'm pretty sure the wiring is sound. Can't wait to get to the bottom of this issue finally so I can spend my weekends tarting up my rocker covers and plenum instead of fault finding.
Tidied up a few things in the engine bay this morning, cable tied one of the lambda wires away from the manifold as it was touching and I imagine getting very hot. Tried wiggling all the wiring in the back of the AFM whilst running and made no difference so I'm pretty sure the wiring is sound. Can't wait to get to the bottom of this issue finally so I can spend my weekends tarting up my rocker covers and plenum instead of fault finding.
I'll get hold of one of those heat shields too because the AFM seems to be working fine in the colder weather we've had this weekend. Still will log my drives in traffic this week as that's where she's misbehaved.
Logged a run out today and nothing untoward to report. Made the below graph of lambda short term trim percentage for both banks, seems to be fluctuating fine but over the whole 20 minute drive (short fuel stop about 1/4 in) it seems to average around +30%. Is that normal?
Logged a run out today and nothing untoward to report. Made the below graph of lambda short term trim percentage for both banks, seems to be fluctuating fine but over the whole 20 minute drive (short fuel stop about 1/4 in) it seems to average around +30%. Is that normal?
Thanks Blitz.
Ok so logged this evening's drive home still on the old MAF. Was fine on the way back fans only cut in 3 times. MAF worked fine throughout. Car did nearly stall itself again upon startup but sorted itself out after a few seconds- my stepper motor value starts at 100% then drops to c.77% for about a second and a half then rises back up to 99% to stop it stalling, then slowly creeps down as you'd expect. Is this normal, or is this what's causing my near stalls on startup? Water and fuel temp reading 26 and 27 degrees C at that point.
Got home fine, parked up and put the roof on, fuel temp reading at 36 degrees C, water temp at 93 degrees. Went to start the car back up to do a revving video for an uncle, still logging- MAF is dead, reading straight up 0% constantly even when fiddling with the connector. Car runs super rich map and then super lean every half second as it tries to keep the car idling smoothly, wreaks of fuel. Fuel temperature is now registering 47 degrees C where the car has been sitting for a few minutes and the heat soak has I reckon got to the MAF.
I'm going to see how things go with the new MAF but think the heat is cooking it, then compounded by a hot running engine when it does fail due to poor fuelling. It will, I'm sure be fine in the morning as it was yesterday and the day before. I think I'm going to try getting both the insulating jacket for it and the heat shield and see what happens.
Ok so logged this evening's drive home still on the old MAF. Was fine on the way back fans only cut in 3 times. MAF worked fine throughout. Car did nearly stall itself again upon startup but sorted itself out after a few seconds- my stepper motor value starts at 100% then drops to c.77% for about a second and a half then rises back up to 99% to stop it stalling, then slowly creeps down as you'd expect. Is this normal, or is this what's causing my near stalls on startup? Water and fuel temp reading 26 and 27 degrees C at that point.
Got home fine, parked up and put the roof on, fuel temp reading at 36 degrees C, water temp at 93 degrees. Went to start the car back up to do a revving video for an uncle, still logging- MAF is dead, reading straight up 0% constantly even when fiddling with the connector. Car runs super rich map and then super lean every half second as it tries to keep the car idling smoothly, wreaks of fuel. Fuel temperature is now registering 47 degrees C where the car has been sitting for a few minutes and the heat soak has I reckon got to the MAF.
I'm going to see how things go with the new MAF but think the heat is cooking it, then compounded by a hot running engine when it does fail due to poor fuelling. It will, I'm sure be fine in the morning as it was yesterday and the day before. I think I'm going to try getting both the insulating jacket for it and the heat shield and see what happens.
Managed to fit the new MAF in the car park at work and I can say its been working perfectly so far. I have also ordered a heat shield from ACT which is my first step in keeping the new MAF cool. If it gets cooked again then I'll go and get one of Zubak's MAF insualting jackets as well.
Haven't taken any readings on fuel economy yet but in terms of how it drives, the Britpart MAF is fine. Haven't yet tested it's thermal resistance in stationary 30 degree heat but got all of summer to do so. Also the issue with the nearly cutting out just after starting has cured itself after fitting a new MAF, not sure if related but good news.
Haven't taken any readings on fuel economy yet but in terms of how it drives, the Britpart MAF is fine. Haven't yet tested it's thermal resistance in stationary 30 degree heat but got all of summer to do so. Also the issue with the nearly cutting out just after starting has cured itself after fitting a new MAF, not sure if related but good news.
Final update on this issue. Since replacing the MAF with a Britpart one and fitting the ACT CF heatshield she's been perfect. MPG is 30-40% better now and the car is not showing any of the previous idling issues on cold start. As a precaution, once up to temperature I run the fans when below 20mph to minimise the chance of manifold to MAF heat soak. In the 30+ degree heat we've been having recently she's been a dream.
Time for a facelift
Time for a facelift
Gassing Station | Chimaera | Top of Page | What's New | My Stuff